Update UPGRADE-2.0.md

Co-authored-by: Andreas Braun <git@alcaeus.org>

Author: jmikola

UPGRADE-2.0.md

@@ -43,7 +43,7 @@ UPGRADE FROM 1.x to 2.0
    is now consistent with validation for other option types.
  * Removed the following driver options from `MongoDB\Driver\Manager`:
    `allow_invalid_hostname` (use `tlsAllowInvalidHostnames` URI option instead),
-   `ca_file` (use ``tlsCAFile`), `context`,
+   `ca_file` (use `tlsCAFile`), `context`,
    `pem_file` (use `tlsCertificateKeyFile`),
    `pem_pwd` (use `tlsCertificateKeyFilePassword`), and
    `weak_cert_validation` (use `tlsAllowInvalidCertificates`).